The present invention is based on a device for determining at least one parameter of a medium flowing in a duct according to the preamble of claim 1.
German Patent Application 197 35 664 A1 describes a device in which a plug sensor having a measuring element is situated within a pipe through which the medium flows, an upstream end of the pipe extending to a filter chamber. However, whirls are formed in the area of the incident-flow edge of the inner pipe, resulting in increased signal noise at the measuring element.
German Patent Application 196 52 753 A1 describes a device having a measuring element, which contains a flow straightener for straightening the flow and a screen for stabilizing a measuring signal. However, no inner pipe is used in this device to protect the measuring element against the effect of dirt particles or water droplets.